1 /*
   2  * Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "jvm.h"
  27 #include "logging/log.hpp"
  28 #include "memory/allocation.inline.hpp"
  29 #include "runtime/arguments.hpp"
  30 #include "runtime/java.hpp"
  31 #include "runtime/mutex.hpp"
  32 #include "runtime/mutexLocker.hpp"
  33 #include "runtime/orderAccess.hpp"
  34 #include "runtime/os.hpp"
  35 #include "runtime/perfData.hpp"
  36 #include "runtime/perfMemory.hpp"
  37 #include "runtime/safepoint.hpp"
  38 #include "runtime/statSampler.hpp"
  39 #include "utilities/align.hpp"
  40 #include "utilities/globalDefinitions.hpp"
  41 
  42 // Prefix of performance data file.
  43 const char               PERFDATA_NAME[] = "hsperfdata";
  44 
  45 // Add 1 for the '_' character between PERFDATA_NAME and pid. The '\0' terminating
  46 // character will be included in the sizeof(PERFDATA_NAME) operation.
  47 static const size_t PERFDATA_FILENAME_LEN = sizeof(PERFDATA_NAME) +
  48                                             UINT_CHARS + 1;
  49 
  50 char*                    PerfMemory::_start = NULL;
  51 char*                    PerfMemory::_end = NULL;
  52 char*                    PerfMemory::_top = NULL;
  53 size_t                   PerfMemory::_capacity = 0;
  54 int                      PerfMemory::_initialized = false;
  55 PerfDataPrologue*        PerfMemory::_prologue = NULL;
  56 bool                     PerfMemory::_destroyed = false;
  57 
  58 void perfMemory_init() {
  59 
  60   if (!UsePerfData) return;
  61 
  62   PerfMemory::initialize();
  63 }
  64 
  65 void perfMemory_exit() {
  66 
  67   if (!UsePerfData) return;
  68   if (!PerfMemory::is_usable()) return;
  69 
  70   // Only destroy PerfData objects if we're at a safepoint and the
  71   // StatSampler is not active. Otherwise, we risk removing PerfData
  72   // objects that are currently being used by running JavaThreads
  73   // or the StatSampler. This method is invoked while we are not at
  74   // a safepoint during a VM abort so leaving the PerfData objects
  75   // around may also help diagnose the failure. In rare cases,
  76   // PerfData objects are used in parallel with a safepoint. See
  77   // the work around in PerfDataManager::destroy().
  78   //
  79   if (SafepointSynchronize::is_at_safepoint() && !StatSampler::is_active()) {
  80     PerfDataManager::destroy();
  81   }
  82 
  83   // Remove the persistent external resources, if any. This method
  84   // does not unmap or invalidate any virtual memory allocated during
  85   // initialization.
  86   //
  87   PerfMemory::destroy();
  88 }
  89 
  90 void PerfMemory::initialize() {
  91 
  92   if (is_initialized())
  93     // initialization already performed
  94     return;
  95 
  96   size_t capacity = align_up(PerfDataMemorySize,
  97                              os::vm_allocation_granularity());
  98 
  99   log_debug(perf, memops)("PerfDataMemorySize = " SIZE_FORMAT ","
 100                           " os::vm_allocation_granularity = %d,"
 101                           " adjusted size = " SIZE_FORMAT,
 102                           PerfDataMemorySize,
 103                           os::vm_allocation_granularity(),
 104                           capacity);
 105 
 106   // allocate PerfData memory region
 107   create_memory_region(capacity);
 108 
 109   if (_start == NULL) {
 110 
 111     // the PerfMemory region could not be created as desired. Rather
 112     // than terminating the JVM, we revert to creating the instrumentation
 113     // on the C heap. When running in this mode, external monitoring
 114     // clients cannot attach to and monitor this JVM.
 115     //
 116     // the warning is issued only in debug mode in order to avoid
 117     // additional output to the stdout or stderr output streams.
 118     //
 119     if (PrintMiscellaneous && Verbose) {
 120       warning("Could not create PerfData Memory region, reverting to malloc");
 121     }
 122 
 123     _prologue = NEW_C_HEAP_OBJ(PerfDataPrologue, mtInternal);
 124   }
 125   else {
 126 
 127     // the PerfMemory region was created as expected.
 128 
 129     log_debug(perf, memops)("PerfMemory created: address = " INTPTR_FORMAT ","
 130                             " size = " SIZE_FORMAT,
 131                             p2i(_start),
 132                             _capacity);
 133 
 134     _prologue = (PerfDataPrologue *)_start;
 135     _end = _start + _capacity;
 136     _top = _start + sizeof(PerfDataPrologue);
 137   }
 138 
 139   assert(_prologue != NULL, "prologue pointer must be initialized");
 140 
 141 #ifdef VM_LITTLE_ENDIAN
 142   _prologue->magic = (jint)0xc0c0feca;
 143   _prologue->byte_order = PERFDATA_LITTLE_ENDIAN;
 144 #else
 145   _prologue->magic = (jint)0xcafec0c0;
 146   _prologue->byte_order = PERFDATA_BIG_ENDIAN;
 147 #endif
 148 
 149   _prologue->major_version = PERFDATA_MAJOR_VERSION;
 150   _prologue->minor_version = PERFDATA_MINOR_VERSION;
 151   _prologue->accessible = 0;
 152 
 153   _prologue->entry_offset = sizeof(PerfDataPrologue);
 154   _prologue->num_entries = 0;
 155   _prologue->used = 0;
 156   _prologue->overflow = 0;
 157   _prologue->mod_time_stamp = 0;
 158 
 159   OrderAccess::release_store(&_initialized, 1);
 160 }
 161 
 162 void PerfMemory::destroy() {
 163 
 164   if (!is_usable()) return;
 165 
 166   if (_start != NULL && _prologue->overflow != 0) {
 167 
 168     // This state indicates that the contiguous memory region exists and
 169     // that it wasn't large enough to hold all the counters. In this case,
 170     // we output a warning message to the user on exit if the -XX:+Verbose
 171     // flag is set (a debug only flag). External monitoring tools can detect
 172     // this condition by monitoring the _prologue->overflow word.
 173     //
 174     // There are two tunables that can help resolve this issue:
 175     //   - increase the size of the PerfMemory with -XX:PerfDataMemorySize=<n>
 176     //   - decrease the maximum string constant length with
 177     //     -XX:PerfMaxStringConstLength=<n>
 178     //
 179     if (PrintMiscellaneous && Verbose) {
 180       warning("PerfMemory Overflow Occurred.\n"
 181               "\tCapacity = " SIZE_FORMAT " bytes"
 182               "  Used = " SIZE_FORMAT " bytes"
 183               "  Overflow = " INT32_FORMAT " bytes"
 184               "\n\tUse -XX:PerfDataMemorySize=<size> to specify larger size.",
 185               PerfMemory::capacity(),
 186               PerfMemory::used(),
 187               _prologue->overflow);
 188     }
 189   }
 190 
 191   if (_start != NULL) {
 192 
 193     // this state indicates that the contiguous memory region was successfully
 194     // and that persistent resources may need to be cleaned up. This is
 195     // expected to be the typical condition.
 196     //
 197     delete_memory_region();
 198   }
 199 
 200   _destroyed = true;
 201 }
 202 
 203 // allocate an aligned block of memory from the PerfData memory
 204 // region. This method assumes that the PerfData memory region
 205 // was aligned on a double word boundary when created.
 206 //
 207 char* PerfMemory::alloc(size_t size) {
 208 
 209   if (!UsePerfData) return NULL;
 210 
 211   MutexLocker ml(PerfDataMemAlloc_lock);
 212 
 213   assert(is_usable(), "called before init or after destroy");
 214 
 215   // check that there is enough memory for this request
 216   if ((_top + size) >= _end) {
 217 
 218     _prologue->overflow += (jint)size;
 219 
 220     return NULL;
 221   }
 222 
 223   char* result = _top;
 224 
 225   _top += size;
 226 
 227   assert(contains(result), "PerfData memory pointer out of range");
 228 
 229   _prologue->used = (jint)used();
 230   _prologue->num_entries = _prologue->num_entries + 1;
 231 
 232   return result;
 233 }
 234 
 235 void PerfMemory::mark_updated() {
 236   if (!UsePerfData) return;
 237 
 238   assert(is_usable(), "called before init or after destroy");
 239 
 240   _prologue->mod_time_stamp = os::elapsed_counter();
 241 }
 242 
 243 // Returns the complete path including the file name of performance data file.
 244 // Caller is expected to release the allocated memory.
 245 char* PerfMemory::get_perfdata_file_path() {
 246   char* dest_file = NULL;
 247 
 248   if (PerfDataSaveFile != NULL) {
 249     // dest_file_name stores the validated file name if file_name
 250     // contains %p which will be replaced by pid.
 251     dest_file = NEW_C_HEAP_ARRAY(char, JVM_MAXPATHLEN, mtInternal);
 252     if(!Arguments::copy_expand_pid(PerfDataSaveFile, strlen(PerfDataSaveFile),
 253                                    dest_file, JVM_MAXPATHLEN)) {
 254       FREE_C_HEAP_ARRAY(char, dest_file);
 255       if (PrintMiscellaneous && Verbose) {
 256         warning("Invalid performance data file path name specified, "\
 257                 "fall back to a default name");
 258       }
 259     } else {
 260       return dest_file;
 261     }
 262   }
 263   // create the name of the file for retaining the instrumentation memory.
 264   dest_file = NEW_C_HEAP_ARRAY(char, PERFDATA_FILENAME_LEN, mtInternal);
 265   jio_snprintf(dest_file, PERFDATA_FILENAME_LEN,
 266                "%s_%d", PERFDATA_NAME, os::current_process_id());
 267 
 268   return dest_file;
 269 }
 270 
 271 bool PerfMemory::is_initialized() {
 272   return OrderAccess::load_acquire(&_initialized) != 0;
 273 }